Another little factoid, from Roddenberry's memoirs.
After the first pilot, network executives hated the characters for both Number One and Mr. Spock. Gene fought a bit, but eventually they told him that he had to get rid of one of them if he wanted to try for a second pilot.
He wrote: "So I decided to keep Mr. Spock and to marry Majel. After all, I couldn't very well have done it the other way around."
-S'Cipio